What Prop for new 2015 Mercury 115 4 stroke Command Thrust?

[jamfandango]

The 115 2 stroke on my 1996 30' Party Hut called it quits late this season so I decided to bite the bullet and re-power.

After looking around and researching option, the new 2015 2.1 liter Mercury 4 strokes seemed like the obvious choice. That allowed me to keep my existing controls and gauges with a basic adapter.

I went with the Command Thrust option since it has a larger lower unit and will spin a larger prop. In theory this should give me more control around the dock with the big girl in the wind.

The engine is on its way for installation so now the question is, what prop should I use? Any insight from those who've gone to a 4 stroke on a ~30 footer?

[ron nh]

I have a 13.5x17 but my boats 18'. It fly's at 5400 rpm's. The 115 CT can spin the same prop as the 150 so the enertia is in play if you want to pay up.

[jamfandango]

Thanks for the feedback.

I did the prop calculator on the Merc site and it seems to be calculating a 12.94 pitch based on my weight input.

They recommend several ones but it seems like a 13x16 Black Max would work best. . .? I don't see the difference between the two 13x16s below.

They didn't even recommend and Enertia option...


PROPELLER MATERIAL BLADES DIAMETER PITCH ROTATION PART #
Black Max® Mercalloy 3 16 12 RH 16436A45
Black Max® Mercalloy 3 16 12 RH 16436CP1
Black Max® Mercalloy 3 16 13 RH 78114CP1
Black Max® Mercalloy 3 16 13 RH 78114A45
Black Max® Mercalloy 3 16 14 RH 16438CP1
Black Max® Mercalloy 3 16 14 RH 16438A45
Mirage® Plus Stainless Steel 3 16 13 RH 826072A46

[rancherlee]

you do NOT want a small 13" diameter prop on that engine, I would look for a 15+" diameter prop in a 13 or 14 pitch for your application. That 120+hp engine with a beefy 2.38 gear case will blow out small props with ease.

[ron nh]

Mine blows out with heavy drag toys often. would you recommend a 4 blade or just larger 3? never had it happen unless tubing. I hit 42 mph gps with nothing on board, it will do 40 with 2 people and my stuff so I'm not looking to add speed at all. should i just get a different prop for sports? sorry to highjack, just got me thinking. My boat probably weighs at least 500lb less than his.

[Xscash]

I will agree, a small prop will just blow out as it did on mine.....no forward power and huge cavatation. I have a 15 X 15 enertia for sale lightly used if you want to try that. But I would guess you may need a smaller pitch.

[jamfandango]

you do NOT want a small 13" diameter prop on that engine, I would look for a 15+" diameter prop in a 13 or 14 pitch for your application. That 120+hp engine with a beefy 2.38 gear case will blow out small props with ease.

So, I had the order of the prop numbers wrong on my previous post...

Looks like the Mercury site is recommending a 16 inch diameter prop with a 12, 13 or 14 pitch. This is my first foray into outboards, so I am still learning some of the principles...

Sound like the 16x13 or 16x14 is the ticket.